Antenna sleet melting apparatus



JulylB, 1935. E. J. STI-:RBA

` ANTENNA SLEET MELTING APPARATUS 2 sheets-sheet 1' Filed Aug. l, 1929 www@ Htl 1 /NI/f/vo/P E. J STERBA July 16, 1935. E, 1 STERBA 2,008,266

ANTENNA SLEET MELTING APPARATUS Filed Aug. 1, 1929 2 sheets-Shed 2 LOW SDL/RC5 BYE. J STE/PBA Patented July 16, 1935 UNITED STATES l' PA-'r-EN'fl OFFICE ErnestJ. Sterba, Asbury Park, `NfJ., assigner to Bell Telephone Laboratories,V Incorporated, s New Ycrk, N. Y., a corporation of New York r Application AugustV 1, 1929, serial No. 382,702 l i 21 claims. '(ox. 25o- 33) This-invention relates to aerial systems and more particularly to such systems as are equipped with means for removing sleet therefrom.

In` the operation and maintenance of both A transmitting and receiving antenna systems located in sections of the-country which are ysubject to sleet storms, considerable trouble is at present experienced because of the formation and the presenceof sleet and ice on theradiating members of the system'. The added weight ofthe ice tends to'detune aerial systems asa result of the change in the dielectric constant of the medium surrounding the wires, the ice having a constant of 80.` It also frequently causes an-actual seve-rence of the radiating elements which usually results in a complete interruption of the operation of the system. y Practically all of the schemes at present employed for removing the sleet possess the disadvantage that it is usually necessary, unless Vrelatively expensive filter apparatus is employed, to disconnect the radio frequency apparatus from the system during the time the low frequency or direct current is being `applied to heat vthe wires. It is an object of thisinvention to supply low frequency energy to a pluralityv of conductors and, at the same time to supply energy of a higher frequency in parallel to either the Whole plurality of the conductors or a portion thereof.

It is another object of this invention to simultaneously energize a radiating system with direct or low frequency currentfor` heating andhigh frequency current for radiation.V

Itis another object of this invention to arrange a plurality of antennae units or groups of units in series for the sleet melting current and, at the same time, in parallel for the radio frequency current.

It is still another object of this invention to supply sleetmelting current to all of the panels of an` exciter or exciter-reflector system, such as disclosed in my copending application Serial No.r

382,103., filed July 30, 1929, and radio frequency current in parallel to the panels of the exciter only, using simple and inexpensive apparatus for doing the same.

- One feature of the invention resides inthe use of a Wave impedance comprising a line, anoddl multiple of a quarter wave length long? shortcircuited at one l end for the radio frequency current, as a `means of providing a path for the sleet melting current and also as a means of preventing the flow of the high frequency current to certain parts of the radiating system. Since one end-of the quarter Wave length is shortcircuited, in a manner such that the load impedance at the given frequency becomes substantially equal to zero, the sending impedance becomes practically infinite for waves of the given frequency; and consequently the wave impedance acts as a low pass lter for separating the paths of the sleet melting and radio frequency currents. Under certain conditions it has been found practicable to utilize a portion of the aerial -system connected in a two-fold circuit relationship with the remaining portion of the system, as a. means of obtaining the desired distribution of thehigh frequency and sleet melting current. Theabove feature and other features will be more apparent from-the following description taken in connection vwith the drawings in which:

Fig. 1 represents one embodiment of the inventionin a wave antenna system comprising an even `number of units or panels;

Fig. 17A shows, symbolically, the impedance transformer'and waveimpedances; i 1 Fig. 2 represents another specific embodiment of the invention in a uni-laterally directive antenna system consisting of an odd number of exciter-reflector panels; Fig. 2A shows the manner of connecting the reflector panels of Fig. 2 in parallel with each other; and Fig. 3 shows still another application ofthe invention in a-fourpanel uni-laterally directive antenna and associated transmission system.

In Fig. l'referencenumerals I and 2 designate any suitable type of closedantenna unit or panel as, for example, the panels described in my copending application. referred to above. In that particular `system -the vertical elements serve as radiating members and the horizontal elements as transmission lines. All elements except the top and bottom vertical elements are one-half Wave length long and thev panels are one-half wave. length apart. rIl'he horizontal elements are so inter-related that radiation therefrom is Aeffectively suppressed. The panels are insulated from the ground by means of insulators I. Y

Reference numerals 3 and 4 represent feeder linesdirectlyconnected at one end to panels I and `2, respectively, and connected at junctionv A- to the main line 5. The other endof line 5 is connected throughan impedance transformer' 6 to any type of radio frequency translation apparatus 6' such as a receiver or transmitter and also to the source of power 'l' for melting the' sleet. The impedance transformer is shown in more detail in FiglA and is similar in construction to that disclosed in my copending application referred to above. The current for melting the sleet will hereinafter be referred to as loW frequency current and it should be understood` that direct current is thereby included since the latter has zero frequency.

VCondensers 1 are inserted at junction A in the feeder lines for the purpose of connecting panels I and 2 in parallel for the high frequency energy, that is, their capacity is such that low frequency currents are effectively blocked and only high or radio frequency currents are passed. Line 5 is connected to the proper terminals of the two lcondensers for placing each of condensers 1 effectively in series with adifferent side of the line and a different panel of the antenn.

The reference numeral 8 designates a wave impedance, each terminal of which is connected to one side of the line 5 through oney of condensers 1. This impedance is symbolically shown in`Fig. lA. It` comprises two parallel conductors, preferablyv copper tubing, an odd multiple of a quarter Wave length long and short circuited-at the far end hereinafter Areferred to as the receiver end by means of a solid metallic bar or othersuitable connection. 'Such a line offers substantially infinite impedance to waves ofthe given frequency, since as pointed out in the above mentioned application, the sendingk impedance of ra quarter wave line is equal" to the square of the 9 comprising condenser I0 and conductors II'.

This wave impedance is similar to-that denoted by numeral 8 mentioned above except that its receiver end is short circuted with respect to high frequency energy by means of a condenser instead of a conductive bar.

Referring, to Fig. lA the symbols representing theimpedance transformer and the two types of wave impedances discussed above are shown in detail. -The impedance transformer vis illustrated byfmeans of heavy lines I2' which represent` conductors an odd multiple of a quarter wave length long to the terminals of which are connected the conductors of a transmission` line.

`When the system shown in Fig` 1 is employed in conjunction with a transmitten'both the low frequency sleet melting current and the radio frequency current are supplied over the main line 5 simultaneously to the system. Assuming that direct current is employed for the sleet melting current itV will be seen that the current from source 1 coming in over one sideof the line that is, the side at the right in the figure fiows through wave impedance 9' transformer E and thence through one panel, wave impedance 8, the

other panel, again through wave transformer 6 andnally back to the source through wave transformerg. .The blocking condensers 1 prevent it from flowing throughthe two panels inparallel and condensers 8 prevent it from flowing to The radio frequency current passes through the condensers 8 and 1 and thence through the two panels Yin parallel. Because of the infinite impedance of the wave impedance at the frequency employed, practically none of this latter energy passes through impedance 8. Similarly, none of this high frequency-energy passes through wave impedance 9 to source 1. Obviousdirectional antenna system and associated transmission system are shown in which are incorporated other features of the invention. Reference numerals 9,10 and II denote three exciter panels and numerals I2, I3and I4 the associated reflector-panels, which are similar in design to the radiating panels described in connection with Fig. 1. The panels are separated from the ground electrically by means of insulators 2. The reflector is one fourth of a wave length to the rear ofand parallel with the exciter. Since it is desirable to supply the same amount of sleet melting energy to all antenna elements and the transmission line a convenient method of effecting this purpose is to connect the panels in series for this type of' current, as explained below, although any proper shunt arrangement may be utilized. Similarly, the reflector panels may be connected in parallel as shown in Fig. 2A which is self explanatory, although thepreferable manner is in vseries as shown in Fig. 2. In Figs. 2 and 2A like reference numerals vdesignate elements of similar function. Y v y VThe main transmission line from the sleet melting power source I8 and radio frequency transmitting or receiving apparatus I9f is designated by numeral I5. Numeral 20' designates low frequency blocking condensers and numeral 2I av wave impedance comprising conductors 22 Vand condenser 23. At junction B the two condensers I6,.one`in each side of the line, serve as low frequency blocking condensers. One wave impedance I1 provides a direct current or low frequency path for connecting the reflector panels, which are in series with eachother, with the exciter panels which, as explained hereinafter, are'also in series with each other. The reference numeral I8 designates a quarter wave line located an even quarter wave length away from junction B and forming in cooperation-with high pass condensers I9, I 9 and 20 an anti-resonant circuit for preventing high frequency current from entering the reflector curtain. The distances between impedance I8 and condenser I9', and between condenser IS and each of condensers 20 are each equal to an odd multiple of a quarter wave length, since this is the optimum anti-resonant arrangement. It should be noted here that the wave impedances of the type such as,V I1, or of the type such as that comprising line I8 and condensers I9, I 9 and 20, are both in series with the active or exciter panels and in shunt to the inactive or reflector panels.

Reference numeral 2I designates a quarter wave line impedance transformer and is utilized here for transforming* the parallel load impedance of the exciter panels into the proper surge impedance for terminating the main line I5. The distance between transformer 2| and junction B is an even `multiple of a quarter wave length so that the impedance at the sending end of transformer 2I is transferred to junction B without substantial change.

At junction C panels 9, I0 and I I are connected through condensers 22 in parallel for the radio frequency current and in series for the sleet melting current in a manner similar to that employed in thearrangement of Fig. l. `Panel I9, the odd panel, is used in one sense in place of the Wave impedance 8 of Fig. 1, that is, unlike the wave impedance it, of course, does not offer innite impedance to the high frequency current, although it does provide a means of connecting panels 9V and II in series for the sleet melting current. t is obvious that additional exciter panels may be connected to panels 9 and II, in parallel for both types of current; and that additional reflector panels may be associated in shunt or in series with reflector panels I2, I3 and I4.

The operation of the system shown inFig. 2 may be described as follows. Both sleet melting current and high frequency energy are conducted over the main line I5. If direct current is employed the sleet melting current from source I3' passes, for instance, through one side of imped-` ance 2l', over the left `conductor of line I5, through one side of impedance I8, reflector panels I2,. I3 and I4, successively, in the order named, through the other side of impedance I8, one side of transformer 2i; exciter panels 3, I0 and II serially, the other side of transformer 2l, Wave impedance I1, right conductor of line I5, other side of impedance 2l and thence to source I8. The radio frequency energy passes through condensers 29 and I6, transformer 2l, condensers 22 and then to the exciter panels 9, I9 and II in parallel. Practically none of this latter energy reaches the reflector panels because of the anti-resonant circuit in the reflector feeder lines.

In Fig. 3 a uni-laterally directive antenna and transmission arrangement is shown which illustrates one method of employing the invention in a four-panel system. In this figure the source of the radio frequency energy and the source of low-frequency sleet melting current are desig` nated by the reference numerals 23 and 24, respectively. In practice a direct current generator supplying 150 amperes at 1,000 Volts has been found suitable for sleet melting purposes in a systern such as shown in this figure.` The quarter Wave line 25 and condensers 25 and 21, the latter condenser being a quarter Wave length from the source 24 and from condenser 26, comprise an anti-resonant circuit at the frequency of the energy supplied by source 23. Condenser 21 merely insures a better capacity short-circuit for the radio frequency energy, that is7 currents of this frequency leaking past condenser 25 pass through condenser 21. Because of the quarter wave length spacing from condenser 2B condenser 21 is located at the point of maximum leak current flow. Condensers 28 are low frequency blocking condensers which prevent energy from source 24 from interfering with that supplied by source 23 or with the transmitting apparatus.

The reference numeral 29 denotes an `impedance transformer employed to obtain the proper terminating impedance for line 33. At junction D three branch lines 3i, 32 and 33 are connected to the main line 39, one conductor of each of lines 3| and 33 being conductively connected to opposite conductors of the main line 33, and the other Vconductor of these lines being associated through one of the low frequency blocking condensers 34 to the remaining opposite mainline conductor. Each of the conductors of line 32 is connected to the main line 33 through one of condensers 34.

The branch line 3l serves as a means of supplying radio frequency and sleet melting energy to the exciter panels 36 and 31 andsleet melting energy to the associated reflector panels 38 and 39; in a symmetrical manner `branch line 33 supplies energy to exciter panels 49 and 4I and reflector panels 42 and 43. Line 32 is terminated in a Wave impedance 35. Reference numerals 44 and 45 designate additional impedance transformers employed for transforming the load impedance at the points'indicated into any desired impedance. The panels are supported by messenger Wires 46 suspended between' antenna towers` 41. Insulators 3 and 4 serve to insulate the panels from the ground and messenger Wires respectively; and insulators 5 electrically separate themessenger Wires from the towers.

In a manner similarto that shown in Figs. Y1 and 2 panels 36 l.and-31 are connected in parallel lto each other for high frequency distribution through high-pass condensers 43 and in series with each other and With the serially connected reflector panels 38 and- 39 for the distribution of the sleet melting current. It should be noted that` the reflector panels are utilized here in place of a wave impedancesuch as designated 8 in Fig. l, or an odd panel such as I in Fig. 2, as a means of Vconnecting the active panels in series for the sleet melting current. The branch line 3| is connected to condensers 48 in the manner described in connection with Fig. 1L Quarter wave line 49 is shorted by condensers 50, I and 52 to form an anti-resonant circuit for the high frequency Waves. Condensers 59 and 5I, and 5I and 52, are an odd multiple of a quarter Wave length apart as explained in connection With the anti-resonant circuit comprising line 25 and condensers 26 and 21, the additional condensers 5I and 52 merely provide a path for the high frequency energy leaking past condenser 50.

In a manner similar to that outlinedabove exciter panels 43 and 4I are connected to the branch line 33 through condensers 53. These panels are likewise in parallel for the high frequency current and in series with each other and with refiector panels 42 and 43, for the sleet melting current. The reflector panels 42 and 43 are in series with each other. The anti-resonant circuit comprising quarter Wave length line 54 and condensers 55, 53 and 51 effectively prevent high frequency current from passing` to the reflector and, as in the other anti-resonant circuits described herein, the condensers` are preferably an odd multiple of a quarter Wave length apart.

The operation of the complete system is obvious from the description given in connection With Figs. l and 2 and need not be repeated here in detail. Briefly stated sleet melting direct current from source 24 flows over the bottom side of line 39 shown in the figure, through transformers t 29 and 44, panels 31, 39, 38 and 35 in the order named, transformer 44, wave impedance 35, transformer 45, panels 4|, 43, 42'and 45 serially, transformer and thence to the opposite'side of both transformer 29 and line 3i! to source 24. High frequency current flows through condensers at junction D, E and F in parallel toi 'panels 33, 31, 49 and 4I, the high frequency energy being effectively prevented from entering the reflector panels. a

Although the various features of the invention have been described in connection with one type of Wave antenna, it should be understood that the invention is applicable to any transmitting or receiving aerial system including both Wave antennae and Yother forms of antennae arrangements and that the invention is not to be limited to the specific embodiments described herein.

It should also be understood that either direct current or alternating current of a frequency lower than the radio frequency current may beV successfully usedfor melting or preventing the formation of sleet on the members of the aerial system.V

. vnatis ciaimedis:

l. In combination, a transmissionline, means for supplying high and low frequency currents connected thereto, a plurality of antenna elements connected inparallel across said line, a pluralityof low frequency blocking impedances oneV of which is included between a terminal of one element and one side of the line and another of Whichis included between a terminal of another element andthe other side of the line, and a high'frequency blocking impedance included between said terminals.

, 2. In combination, a'transrnission line, means for supplying high and low frequency currents connected thereto, a plurality of antenna. elements connected across the line, a plurality of low frequency blocking imp-edances one of which is included in one 'side of the line between -said elements and another of which is included in the other side of Vthe line betweensaid elements and said means, and a plurality of high frequency blocking impedancesone of which is included between at least one of the elements and the lineV and-another of which is included conductively in series with said elements and said means.

3. In combination, a plurality of antenna conductors, a source of energy, a second source of energy, the` frequency of the Venergy i'rorn'the second source being higher than that from the rst mentioned source, said conductors being in series circuit with said low frequency source and at least a portion of said conductors being in parallel with each other and in circuit with said second source.

y 4. In combination, a plurality of vantenna corn ductors, a source of low frequency energy, a translation device, said source being conductively connected to the conductors, said device being connected in circuit with two of these said conductors arranged in parallel with each other, and means for preventinghffh frequency energy from flouing through the remaining antenna conductors.

5. In combination, a plurality of aerial conductors, a source of low frequency energy, a relatively high frequency translation device, said source being conductively connected to said conductors, said device connected in circuit with at leasttwo of said conductors in parallel and means for pre# venting high frequency energy fromv` flowing through the remaining conductors comprising a capacitively short-circuited quarter wave length line inserted between the'rst mentioned and the last mentioned aerial conductors.

V6.*In combination, a plurality of aerial units, each terminal of each of the said units being connected to the corresponding terminals of the other'units through at least one low frequency impedancaga series circuit comprising said units connected in series with each other through at least one high frequency impedance, a high fre- Y quency translation device, a source of low frepedances, the terminals of each panel being connected through a separate impedance to .the terminals of another panel, an oddY antenna panel being connected directly to one 'terminal of each of the panels and through one of the impedances to the other terminal of each panel, a source of Y radio frequency energy, and ak source of low fre-` quency energy, saidsources being vconnected `to said impedances at points opposite from` the odd.

panel.

9. In combination, an antenna `system comprising an exciter anda reflector each compris'- ing a plurality of panels conductively joined, a source-of low frequency current, a first circuit conductively connecting said source with the exciter and reiiector, a sourceof high frequency current, a second circuit connecting the exciter panels in parallel with each other and tothe last mentioned source, a wave impedance or filter comprising a quarter wave length line having substantially zero terminating impedance being included in series with the exciter panelsand in shunt to the ieflectorpanelaand a low frei quency blocking condenser included inthe' second circuit between each two adjacent panels so that the exciter panels areV Vserially connected for low frequency current. f

10. In combination', means for removing sleet from 'an antenna system comprising a low Irequency impedanceinv circuit'with a radio transmitter and a wave impedance in circuit with a source of low frequency power, a portion of the antenna being connected through the wave irnpedance to the source and through the4 low frequency impedance to the radio transmitter.

il. In combination, a wave antenna system comprising an exciterhaving an evenplurality of closed panels and a reflector, leads connecting the panels in parallel and each including a low frequency impedance element', a lead connecting each terminal of theV reiiector to a relatively opposite terminal of a different element, a high frequency impedance included in `the reflector leads and comprising a quarter wave line capacitatively short-circuited at .the end toward the reiiector, atransmitter, a sourceof low frequency powenand common leads from said transmitter and said source Aeach connected to opposite reilector terminals through one of the said elements. Y

l2. In combination, an antenna, a source of high frequency alternating current for energizing said antenna, a source or heating energy for said antenna, means for coupling both of said sources simultaneouslyrto said antenna comprisingV wire connections, and means for preventing flow of radio frequency 4current in the connections to the heating source.

" 13. In combination, an'antenna-a translation device, a source of hcating'energy, means for simultaneously couplirnfsaid device and source to said antenna, an' means for preventing the -flow of radio frequency current in the connections to the heating source when 'antenna and source are coupled. l

i4. In combination, an antenna, a source of radio frequency current therefor. feeders for coupling said source to said antenna, means for neutralizing radiation from said feeders, a source of heating energy, and connections between said last mentioned source and the antenna for supplying heating energy thereto simultaneously with the application of said radio frequency current.

15. In combination, an antenna, a source of radio frequency current therefor, feeders for coupling said source to said antenna, means for neutralizing radiation from said feeders, a source of heating energy, connections between said last mentioned source and the antenna for supplying heating energy thereto simultaneous with the application of said radio frequency current, and means for preventing the flow of high frequency currents in said connections.

16. In combination, an antenna, a source of high frequency energy therefor, feeders coupling the source and the antenna, neutralizers for neutralizing radiation from the feeders, a source of heating energy, and means for connecting the source of heating energy to the antenna and neutralizers for removing frozen deposits therefrom.

17. In an antenna system, a radiating element comprising a pair of radiators, each radiator comprising a pair of Wires paralleled for radio frequency currents and serially connected for heating energy, and means for supplying radio frequency energy and heating energy at the same time to the Wires.

18. In an antenna system, a source of heating energy, a source of radio frequency energy, a radiating element comprising a pair of radiators, each radiator comprising a pair of Wires adapted for simultaneous association with both said sources of energy, said wires being effectively connected in parallel for radio frequency energy and serially connected for heating energy, feeders between said source and said Wires, said feeders being arranged so that there is mutual radiation cancelation therefrom.

19. A radio signalling system having, in combination, high frequency apparatus, a plurality of antenna conductors, a source of relatively W frequency heating energy, said conductors being directly connected with said low frequency source, and at least a portion of said conductors being in parallel with each other and in circuit with said high frequency apparatus, and means for preventing the flow of high frequency current in the conductors to the heating source.

20. In combination, high frequency apparatus, a plurality of antenna conductors, a source of heating energy, said conductors being electrically connected to both said high frequency apparatus and said source, and means for preventing the flow of high frequency current in the conductors to the heating source.

21. In combination, two pairs of antenna conductors, a source of heating energy, and a source of high frequency alternating current, said first source being directly connected to said pairs of conductors, said second source being connected in circuit with said conductors arranged in parallel with respect to each other, and means for preventing the iiow of high frequency current in the conductors to the source of heating energy.

ERNEST J. STERBA. 

